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PCBs and PBDEs on the Guadalupe River

WYs 2003 – 2006

John Oram, Jon Leatherbarrow, and Lester McKee

Sources Pathways and Loadings WorkgroupNovember 13th 2006

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Methods for Estimating Loads of PCBs and PBDEs

1. Examine relationship between instantaneous SSC and contaminant conc.

2. Examine spatial/temporal patterns of precip and Q at various locations in watershed to determine source.

3. Use 1 and 2 to build regression model(s) where appropriate.

4. Use regression model to estimate 15-minute concentrations.

5. Use 15-minute Q and 15-minute conc to calculate loads.

Iter

ativ

e P

roce

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WY 03 (n=21)

WY 04 (n=19)

WY 05 (n=13)

WY 06 (n=14)

Sampling FrequencyItem #2b

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Sampling Frequency Item #2b

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PCBs vs SSC (previous water years)

WY 2005

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PCBs vs SSC WY 2006

• Did not see ‘split’ regression this water year.

y = 76.713x - 2295.7

R2 = 0.9929

y = 65.063x + 10450

R2 = 0.7437

0

10000

20000

30000

40000

50000

60000

0 100 200 300 400 500 600 700 800

SSC (mg/L)

Sum

of P

CB

s (p

g/L) Upper

Lower

Base

Linear (Upper)

Linear (Lower)

y = 75.539x + 4119.6

R2 = 0.7151

0

10000

20000

30000

40000

50000

60000

0 100 200 300 400 500 600 700 800

SSC (mg/L)

Su

m o

f P

CB

s (p

g/L

)

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PBDEs vs SSCWY 2005

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PBDE Concentrations, Discharge, and Instantaneous SSC

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PBDEs vs SSCWY 2006

• Attempted to split regression by upper/lower/base flow designations.– Didn’t work this year

for PBDEs or PCBs

• Two Regressions:

– All data

– No Outlier

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Previously Reported LoadsItem #2b

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WY 2006 LoadsWY 2006 Oct Nov Dec Jan Feb Mar Apr Total Regression EquationDischarge (Mm3) 2.5 2.4 11.5 14.6 6.6 21.9 48.5 108.0Percent of Total 2.3% 2.2% 10.6% 13.6% 6.1% 20.2% 44.9%

SSC (t) 47.8 48.8 1,630.1 1,286.8 732.4 1,539.1 6,466.6 11,751.6Percent of Total 0.4% 0.4% 13.9% 10.9% 6.2% 13.1% 55.0%

PBDEs (Kg) 0.02 0.02 0.66 0.52 0.30 0.63 2.63 4.8 pbdes = 406.53 x SSCPercent of Total 0.4% 0.4% 13.9% 10.9% 6.2% 13.1% 55.0%

PBDEs (Kg) 0.04 0.04 0.55 0.51 0.26 0.66 2.21 4.3 pbdes = 243.48 x SSC + 1.31e4Percent of Total 1.0% 1.0% 12.8% 11.8% 6.2% 15.5% 51.7%

PCBs (Kg) 0.00 0.00 0.16 0.10 0.07 0.05 0.58 1.0 With OutlierPercent of Total 0.0% 0.0% 16.5% 10.7% 7.6% 5.1% 60.0%

PCBs (Kg) 0.01 0.01 0.17 0.16 0.08 0.21 0.69 1.3 No OutlierPercent of Total 1.1% 1.1% 12.8% 11.9% 6.2% 15.5% 51.7%

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Source ID by PCB Homologs?

From WY05 Report

Source activationof ‘new’ PCBs during high flow?

Transport ofweathered material?

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Source ID by PBDE Homologs?Item #2b

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How did WY05 and WY06 compare to previous years?

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How did WY05 and WY06 compare to previous years?

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April 2006• 2.21 Kg PBDEs (52% of Seasonal Load)

• 30% of 2.21 kg delivered on April 4th = 0.73 kg.

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PBDE PCB

Source (kg/yr) (kg/yr)

Wastewater 37 2.5

Small tributaries ~64 9-15

Delta ~11 6-23

Atmosphere 1-2 -7

Total ~114 10-34

Sources: RMP special study on wastewater discharges; L. McKee; CARB (2005); D. Yee

Annual Loading EstimatesPBDE loads are 3-11x PCB loads.

Estimates or Preliminary!

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Modeling PBDEs*Predicted inventories are consistent with those estimated from monitoring.

Source: J. Oram, SFEI

Model predictions are preliminary.

Loads

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